A Calgary-based company, Carbon Engineering is promising to take carbon dioxide of thin air and turn it into a resource. Ambitious as it may sound, carbon capture is a rapidly maturing technology, and Carbon Engineering is taking a demonstration facility in Squamish, BC into operation during 2015. The picture below shows what an array of
air contactors may look like if the design is scale up to a commercial
size.

The company still has a long way to go before the technology
becomes commercially viable. There are engineering challenges,
but more importantly, big economic challenges. Similar
to Inventys, a BC-based company I discussed in my
August 20, 2014 blog,
getting from a smart innovation to a commerically-successful
technology is a difficult path.

The basic idea of how to capture carbon dioxide from thin
air is not new. However, making it efficient is another matter.
Air contactors propel large amounts of air through a type
of scrubber where a capture solution of potassium hydroxide
flows down across contact sheets that take up to 80% of the
carbon dioxide into a water and potassium carbonate solution.
This carbonate solution is then fed into a pellet reactor that
regenerates the solution by bringing it into contact with calcium
hydroxide. This process recovers potassium hydroxide that is
reused as a capture solution, as well as calcium carbonate
that binds the carbon dioxide. The calcium carbonate is separated
from the capture solution and is brought to a fluid-bed
calciner that operates at 900°C and decomposes the
calcium carbonate into pure carbon dioxide and calcium oxide.
The carbon dioxide is captured, and the calcium oxide is
brought into contact with water and reacts to generate
calcium hydroxide. Essentially, there are two separate
chemical cycles at work.

The critical input into the process is energy in the
form of heat. The demonstration plant will burn
natural gas in a pure oxygen environment to generate the required heat
and produces only carbon dioxide, which is also captured.
This process is either relying on the oxyfuel
method, a process to provide pure oxygen from air through
cryogenic separation, or by using electrolysis to separate
oxygen out of water using electricity.

The economic feasibility of the technology hinges
on two cost factors: the fixed cost of building the
air contactor and the regeneration system,
and the variable cost of energy for powering the system
and providing pure oxygen. Eventually, power can also
be provided from clean energy rather than natural gas.
Ideally, carbon capture plants can be placed in
places where clean energy is readily available.
But this opens up another challenge: what to do
with the captured carbon dioxide.

If the ultimate goal is carbon sequestration,
a carbon capture plant needs to be near a suitable
sequestration plant. And this may be in locations where
renewable energy may or may not be readily available.
Alternatively, carbon dioxide can be turned into fuel.
This is indeed what Carbon Engineering has
in mind. Take water and carbon dioxide and clean energy,
and get carbon fuel (e-diesel) in return.

Start with clean energy and water. Use electrolysis to
separate water into hydrogen and oxygen, which
is particularly efficient when applied to super-heated
steam. The hydrogen is then combined with carbon dioxide
in a conversion reactor to produce more hydrogen, water, and
carbon monoxide. Lastly, using the Fischer-Tropsch process,
the syngas made up of hydrogen and carbon monoxide is combined
under high heat and pressure to generate what is known
as blue crude, a synthetic fuel that can be refined into
e-diesel. A demonstration plant was built by clean-tech company
SunFire and the
car manufacturer Audi in the German city of Dresden.

Capturing carbon dioxide out of thin air thus hinges
on one critical element: plentiful and cheap non-fossil
energy. As solar power and wind power become more readily
available, making fuel out of water and thin air may
also help solve the intermittency problems of renewable
energy sources. However, the Achilles Heel of all of these
impressive innnovations is cost. Can these technologies
become commercialy viable? As of today, they are not.
But a decade hence, perhaps?

Meanwhile, if you are passing through Squamish, BC
on the Sea-to-Sky Highway, take a quick detour and
drive by a modest industrial building on
37322 Galbraith Avenue in the city's harbour area.
The air around there will have less carbon dioxide
than elsewhere.

Founded by Harvard University professor David Keith in 2009
and funded by Microsoft Founder Bill Gates,
Carbon Engineering
is one of the eleven finalist in the $25 million
Virgin Earth Challenge,
offered by Richard Branson and former U.S. Vice President Al Gore.